Baseboard & Trim Calculator
Calculate how many linear feet and boards of baseboard or trim a room needs.
Calculator
| 12 ft pieces (+10%) | 4 pieces |
|---|---|
| Linear feet to buy (+10%) | 46 ft |
| Room perimeter minus doors | 42 ft |
How it is calculated
Perimeter = 2 × (12 + 12) = 48 ft, minus 2 door openings (3 ft each) = 42 ft; +10% = 46 ft, or 6 eight-foot pieces.
About this calculator
The amount of baseboard is the room's perimeter minus the width of door openings. Trim is sold in 8- and 12-foot pieces, so you buy a bit more than the exact length to allow for mitered corners and mistakes.
Longer pieces mean fewer joints, but 8-foot lengths are easier to carry and cut. The same method works for crown molding, chair rail and shoe molding.
Worked examples
| Project | 8 ft pieces (+10%) | Rough cost |
|---|---|---|
| a 12x12 ft room | 6 pieces | $46.20 – $231 |
| a 10x14 ft room | 7 pieces | $49.50 – $248 |
| a 16x20 ft room | 9 pieces | $69.30 – $347 |
| a 20x30 ft room | 13 pieces | $96.80 – $484 |
Buying notes
- Let the trim sit in the room for a day or two before installing so it adjusts to the humidity.
- Prime and paint trim before cutting if possible.
- Caulk and nails are extra.
Quick answers by size
Click a size for the exact quantity and cost.
How to measure and use this calculator
- Measure each wall and add them for the room's perimeter.
- Subtract door openings.
- Read the pieces needed in 8 ft or 12 ft lengths.
- Add extra for miters and mistakes.
Common mistakes
- Forgetting that inside corners use up length.
- Buying all short pieces and getting too many joints.
- Not letting the trim acclimate to the room before installing.
Tips
- Longer boards mean fewer joints, but 8 ft is easier to carry.
- Add 10% for miters and mistakes.
- The same method works for crown molding and chair rail.
Frequently asked questions
How much baseboard do I need?
Add up the room's perimeter, subtract door openings, then add about 10%.
How much extra baseboard should I buy?
About 10% extra covers miter cuts and mistakes.
Do I include closets?
Yes, if the closets get baseboard; measure their perimeter and add it.